1. Field of the Invention
The present invention relates generally to a ratchet wrench and more specifically, to a ratchet wrench that has an improved structure strength.
2. Description of the Related Art
FIG. 1 shows a conventional ratchet wrench 1, which comprises a handle 2 and a ratchet head 3 pivotally connected with the handle 2. The handle 2 has two spaced pivoting walls 4 defining a receiving space therebetween at one end of the handle 2. One of the pivoting walls 4 has a threaded through hole 5 and the other has a T-shaped through hole 6, i.e. a counterbore through hole. The ratchet head 3 has a pivoting portion 7 pivotally mounted in the receiving space between the two pivoting walls 4 of the handle 2 by means of a screw 9 running through the T-shaped through hole 6 of the handle 2 and a through hole 8 of the pivoting portion 7 of the ratchet head 3 and threaded with the threaded through hole 5 of the handle 2. When the ratchet wrench 1 is in use, the operation force applied from a user on the handle 2 will be transmitted to the ratchet head 3 through the two pivoting walls 4 for enabling the ratchet head 3 to rotate and fix a workpiece.
As shown in FIG. 1, the threaded through hole 5 of the handle 2 is smaller in diameter than the T-shaped through hole 6 of the handle 2 because of the existence of the threads. Thus, when the strength is transmitted from the handle 2 to the ratchet head 3, an uneven distribution of stress will be exerted on a top section of the screw 9, which is located at the T-shaped hole 6 of the handle 2, and a bottom section of screw 9, which is located at the threaded hole 5 of the handle 2, such that the screw 9 may be broken after the ratchet wrench 1 is used for a long time. Further, the stress concentration will be generated between the screw 9 and one end of the threaded hole 5 of the handle 2 close to the pivoting portion 7 of the ratchet head 3, resulting in acceleration of destruction of the screw 9. Thus, it is desirable to provide a ratchet wrench that can eliminate the aforesaid drawbacks.